High Output Power Density Triboelectric Nanogenerator Based on Surface-Patterned PI/UIO-66-NH2 Mixed Matrix Membranes

Triboelectric nanogenerators (TENGs) have emerged as a promising technology to harvest energy from the environment due to their self-powered characteristics, simple structure, low cost and high flexibility. To improve their performance, this work proposes a hierarchical optimization strategy, which integrates the employment of polyimide (PI) matrix, the doping of metal-organic framework and the surface patterning of TENG triboelectric layers to achieve high output performance and durability. In the work, the PI/UIO-66-NH₂ mixed matrix membrane (MMM) is first synthesized and characterized, where the influence of UIO-66-NH₂ loading amount on the triboelectric properties of MMM is analyzed. The measurement results show that this MMM exhibits excellent dielectric properties and thermal stability. Subsequently, the TENG device operated in the vertical contact-separation mode is fabricated, where MMM is used as the negative triboelectric layer and pure PI membrane as the positive layer. Moreover, the surface patterning method based on soft imprint lithography is applied to both triboelectric layers to augment their effective contact areas. Then, the output performance of TENG is characterized. It is found that, for the weight ratio of UIO-66-NH₂ of 5 wt%, the patterned UIO-66-NH₂ MMM-based TENG (P-TENG-5) achieves a maximum output power density of 78.27 ± 3.42 μW/cm², which is 5.76 times higher than that of unpatterned TENG-5 and 361.35 times greater than that of pure PI-based TENG-0. Remarkably, P-TENG-5 maintained stable performance over 20,000 cycles at 2 Hz without the considerable performance degradation.